Estimation of developed overvoltages at entrance of HV/MV substation

This project dealt with the effective lightning protection of HV/MV substations, examined the impact of various factors on the magnitude of the developed overvoltages at different positions of the system. The influence of the equivalent circuit model of the various components to the calculated overvoltages was also examined. Moreover, the substation outage rate due to lightning strokes was calculated, considering shielding failures and back-flashovers. In addition, special issues are discussed, i.e. induced overvoltages and installation of arresters in parallel. The main contribution of this project is that did not focus only on the role of the grounding resistance, but examined the dominant influence of other parameters; the improvement of the lightning performance of the substation can be achieved by the appropriate adjustment of various factors of the system. This work highlighted the advantages and drawbacks of each equivalent circuit model and provided a guide to other researchers in order to select the appropriate models.